NEW YORK (AP) — Stock indexes didn’t do much at first glance on Monday, but the modest move for the Standard & Poor’s 500 masked some dramatic changes roiling underneath the surface.

Telecom stocks, banks and other areas of the market that stand to benefit the most from Washington’s drive to cut corporate tax rates jumped. At the same time, technology stocks slumped and gave up a chunk of the gains that have made them the best-performing part of the market by far this year.

The New York Stock Exchange was nearly evenly split between stocks that rose and fell, and the split in perfor...